U.S. patent number 4,191,231 [Application Number 05/817,940] was granted by the patent office on 1980-03-04 for flexible collapsible containers, and method of molding.
This patent grant is currently assigned to Baxter Travenol Laboratories, Inc.. Invention is credited to Jerry D. Martin, Frank L. Roe, David A. Winchell.
United States Patent |
4,191,231 |
Winchell , et al. |
March 4, 1980 |
Flexible collapsible containers, and method of molding
Abstract
The method of molding flexible, collapsible containers comprises
extruding a tubular parison of material to be molded and sealing
the outer, free end of the parison; ballooning the parison with
relatively low pneumatic pressure; closing the mold about the
ballooned parison to cause the edges of the parison to protrude out
of the mold chamber; and sealing said parison to form said
container, including the step of forming seal lines positioned
laterally inwardly from the lateral edges of the parison. A novel
container design is also covered.
Inventors: |
Winchell; David A. (Twin Lakes,
WI), Martin; Jerry D. (Kenosha, WI), Roe; Frank L.
(Hanover Park, IL) |
Assignee: |
Baxter Travenol Laboratories,
Inc. (Deerfield, IL)
|
Family
ID: |
25224255 |
Appl.
No.: |
05/817,940 |
Filed: |
July 22, 1977 |
Current U.S.
Class: |
383/14;
128/DIG.24; 604/408; 383/22 |
Current CPC
Class: |
A61J
1/10 (20130101); B29C 49/48 (20130101); B29C
49/18 (20130101); Y10S 128/24 (20130101); B29C
49/04 (20130101) |
Current International
Class: |
A61J
1/00 (20060101); B29C 49/48 (20060101); B29C
49/18 (20060101); B29C 49/00 (20060101); B29C
49/04 (20060101); B65D 035/08 () |
Field of
Search: |
;150/8,1,.5
;128/272,DIG.24,272.3,214D,214B,214C ;141/114 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Moy; Joseph Man-Fu
Attorney, Agent or Firm: Flattery; Paul C. Kirby, Jr.; John
P. Ellis; Garrettson
Claims
That which is claimed is:
1. A blow-molded, flexible, collapsible container, free of
laterally positioned longitudinal seal lines, which defines a
sealed, collapsible portion of generally oval transverse
cross-section and, defined at one end of said sealed portion, a
shoulder portion having a wall thickness substantially thicker than
the wall thickness of the sealed, collapsible portion, a plurality
of spaced, upstanding sleeves being defined through said shoulder
portion at said one end, the oval cross-sections of said sealed,
collapsible portion defining major axes which are at least 50
percent greater than the minor axes of said oval cross-sections to
facilitate flat collapse, and at the end of said container opposite
to said shoulder portion end an integrally-attached, flat tail seal
and hanger portion, said tail seal and hanger portion defining a
continuous inner end integral with the remainder of said container
material and having central and lateral portions, said continuous
inner end being longitudinally recessed toward said container at
its central portion relative to the lateral portions thereof to
permit tucking of the hanger portion into the bag.
2. The flexible, collapsible container of claim 1 including a web
portion connecting said spaced sleeves, and perforatable portions
defined in said web portion to permit the passage therethrough of
alignment rods of a plasma extractor.
3. The container of claim 1 in which the circumferences of
container wall sections in planes perpendicular to the longitudinal
axis of said chamber are essentially all uniform, the portions
adjacent both ends of the chamber tapering transversely to thin
ends, and correspondingly increasing in lateral dimension to
achieve the uniform circumference of said chamber wall
sections.
4. The container of claim 3 in which, apart from the area of said
shoulder portions, the wall thickness of said container is
generally uniform.
5. The container of claim 4 in which the plastic of the container
does not exhibit longitudinal axial orientation.
Description
BACKGROUND OF THE INVENTION
Blood is generally stored in flexible, collapsible containers. The
soft, collapsible, plastic material of the containers permits the
blood to be drained from the containers without bringing it into
contact with vented air in the container.
Various plastic formulations exhibit good characteristics of
compatibility with blood cells. At the present time, most blood
bags are made of polyvinyl chloride formulations, for one reason
because of good Radio Frequency (R.F.) sealing characteristics.
Other plastics are also promising candidates for collapsible blood
bag materials, for example, various copolymers of polyolefins, such
as those containing ethylene, propylene, and/or butylene units, and
copolymers containing other units such as styrene and vinyl
acetate.
Unfortunately, many vinylic polymer materials such as polyolefins
are less susceptible to R.F. sealing. Thus, they are not as readily
manufacturable by the peripheral heat sealing of plastic sheets
together to define the container in the manner analogous to the
present manufacturing process of vinyl blood bags, particularly
when the most desirable thin-walled blood bags are being
manufactured, in which the wall thickness is as low as 0.008 to
0.018 inch, for example. In this case, conventional assembly
methods for blood bags have been found not to produde a container
of adequate strength with, for example, polyolefin-based polymers
having this low wall thickness.
Also, blood bags are usually of a generally oval cross section in
which the major axis of the oval is substantially larger than the
minor axis, e.g. at least 50 percent greater and preferably at
least 100 percent greater.
Another alternative for manufacture of polyolefin-containing
containers and the like is blow molding, in which a tubular parison
is extruded, placed into a blow mold, and then inflated, to conform
to the shape of the inner chamber of the mold. However, it has
proven difficult to blow mold containers of extreme oval cross
section without obtaining substantial differences in the wall
thickness about the circumference of the cross section. This, in
turn, interferes severely with the desired mode of collapsing of
the container.
In accordance with this invention, novel oval containers are
disclosed, having wall thicknesses about their cross section of
improved uniformity, as well as other advantages described below.
These containers can be made so that the container walls are
sufficiently thin to be readily collapsible in the manner of
conventional blood bags, although the use of the container is not
restricted merely to blood bags, but they may be used for any of a
large variety of desired uses for collapsible bags.
DESCRIPTION OF THE INVENTION
In this invention, flexible, collapsible containers, preferably of
the novel type described below, are made by extruding a tubular
parison of material to be molded, and sealing the outer end of the
parison; ballooning the parison with relatively low pneumatic
pressure (for example 5 to 10 p.s.i.g.), closing the mold about
said ballooned parison to cause lateral edges of the ballooned
parison to protrude out of the mold chamber of said mold, and
sealing said parison to form the flexible, collapsible container,
including forming seal lines for the container, by means of the
mold, positioned laterally inwardly from the lateral edges of the
parison.
Preferably, the entire bag is defined by seal lines interior from
the edges of the parison. Thus, the formed bag is surrounded by
what might be called a frame of parison material, which may be
stripped off after formation of the bag.
The invention of this application is easily utilizable to produce
containers of generally oval cross sections, in which the major
axes of the cross sections are at least fifty percent greater than
the minor axes of the cross sections. This is so because the
closing mold chamber, which will be of corresponding shape, simply
presses the parison together to permit the molding of the container
out of a pair of parison face sections, which are generally
surrounded by other portions of the parison for later removal.
The method of this application is preferably utilized on a
container which is formed in the mold without axial stretching, to
avoid an excessive amount of bi-axial orientation, which may
interfere with the formation of strong, peripheral seal lines
defining the container formed out of the parison.
As a further advantage, this invention can be performed with
reduced tolerances relative to parison size and positioning with
respect to the mold, when compared with many other blow molding
techniques, especially those involved with the blow molding of
thin-walled containers of highly oval cross section. Accordingly,
the containers produced in the manufacturing process can be
expected to exhibit fewer rejects, even though less expensive and
precise apparatus is used in the manufacture.
Preferably, when the mold is closed about the parison, relatively
high pneumatic pressure when compared with the relatively low
pneumatic pressure (for example 50 to 120 p.s.i.g.) utilized to
initially balloon the parison, is applied to the parison interior
through access apertures which the mold defines in the container,
to blow mold it into intimate conformity with the shape of the mold
chamber.
It is also preferred to extrude the parison to exhibit an increase
in wall thickness over a relatively minor part of its length, to
provide a substantially increased wall thickness in that portion of
the parison which is to be molded to define the access apertures,
when compared with the majority of the remainder of the parison.
Accordingly, relatively rigid access apertures may be defined in
one end of the container, while the remainder of the container is
thin, flexible and collapsible.
It is also preferred for the collapsible container to be shaped by
the mold so that circumferences of the container wall sections in
planes perpendicular to the longitudinal axis of the chamber are
essentially all oval and uniform, the portions adjacent both ends
of the chamber tapering transversely to thin ends, and
correspondingly increasing in lateral dimension to achieve the
uniform circumference of the chamber wall sections.
Accordingly, by the method described above, flexible, collapsible
bags for blood and other desired uses, having a substantially oval
cross section, may be mass produced on a reliable basis, even when
made from polyolefin-based materials which do not seal well by
conventional R.F. sealing. This also permits the use of plastics in
blood bags having greatly reduced plasticizer content, which is
deemed by many to be desirable.
In the drawings,
FIG. 1 is an elevational view of a blood bag which is manufactured
in accordance with this invention.
FIG. 2 is a side elevational view of the blood bag of FIG. 1,
rotated 90 degrees from the view of FIG. 1 about the longitudinal
axis thereof, with the blood donor tube broken away.
FIGS. 3 through 8 are perspective views of portions of a molding
machine, showing sequential steps in the molding operation of this
invention.
FIG. 9 is an elevational view of one mold half utilized in this
invention, with the newly-formed container shown resting
therein.
Referring to the drawings, blood bag 10 is illustrated defining a
closed, flexible, collapsible container of generally oval cross
section having a shoulder portion 12 with a wall thickness
substantially thicker than the wall thickness of the remainder 14
of the sealed collapsible portion. Specifically, shoulder portion
12 may be from 0.02 to 0.1 inch thick, typically 0.06 inch, while
the remaining portion 14 of bag 10 may range from 0.008 to 0.018
inch, for example 0.013 inch, with relatively little variation in
wall thickness in different portions 14 of the container.
There is defined through shoulder portion 12 a plurality of spaced,
upstanding tubular sleeves 16, 17 projecting outwardly from the end
of the bag to provide communication to the bag interior. Sleeve 16,
as shown, is connected to a donor tubing 18, which terminates in a
conventional needle assembly 20, being connected to sleeve 16 in
the manner shown in the co-pending patent application of David A.
Winchell, et al., Ser. No. 705,319 filed July 14, 1976. The other
sleeves 17 carry molded tubular structures 22, being heat sealed to
the outer ends 24 of sleeves 17. The sleeves 17 define a sealing
diaphragm across their bores which may be penetrated by a sterile
needle for access.
Outside of structure 22 a closed port protector 23 is provided.
Tubular structure 22 and port protector 23 may be of conventional
structure. Structure 22, donor tubing 18, and protectors 23 may be
added after molding of the bag 10.
Sleeves 16, 17 may be interconnected by thin web portions 25
integral with the sleeves. Web member 25 has a perforatable portion
27 defined therein, being perforatable because of the presence of
the line of weakness 29 designed in the web member 25, the line of
weakness being only about 0.001 or 0.002 inch thick and defining a
closed, generally rectangular (or circular if desired) figure so
that web member 27 may be punched out to permit the passage
therethrough of alignment rods of a plasma extractor or other
hanging and orienting members.
At the other end of container or bag 10 an integrally attached,
flat tail seal and hanger portion 26 is provided, being defined
with a perforatable slot 28, to permit penetration of a hanger rod
or hook so that the bag may be hung in inverted position.
Hanger member 26 is shown to be longitudinally recessed toward the
container 10 at its central portion 30 relative to the lateral
portions 32 thereof. This permits the tucking of the hanger portion
into the bulk of the bag during the configuration of the blood bag
after collection of the blood has taken place.
It might also be added that, as an alternative embodiment to the
bag specifically illustrated herein, different numbers of ports 16
may be provided. For example, a fourth port may be provided for
permanent communication with tubing connecting to a second blood
bag, for providing a double bag similar in function to the
presently known double bags. Also, in similar manner, the bag of
this invention may be utilized in conjunction with other multiple
bag systems.
It may be seen from an inspection of FIGS. 1 and 2 that the
circumferences of the container wall section, for example sections
34 and 36, which are perpendicular to the longitudinal axis 38 of
the chamber, are essentially all uniform except at the extreme ends
of the container. This is accomplished by the fact that both ends
of the chamber taper transversely to thin ends as illustrated in
FIG. 2 while correspondingly increasing in lateral dimension as
illustrated in FIG. 1, to achieve the generally uniform
circumference of the chamber wall sections 34, 36 etc. throughout
the great majority of this invention, despite the changing
transverse and lateral dimensions as illustrated in FIGS. 1 and 2.
This arrangement facilitates the flat collapse of the container
despite the fact that it has been molded in oval shape, as further
disclosed for example in Canadian Pat. No. 1,001,511.
The collapsible, uniform-walled, blow molded container of this
invention may be manufactured in accordance with the following
process steps, as illustrated in FIGS. 3 through 9. The apparatus
used for performing the method of this invention may, for example,
be a continuous extrusion machine with a secondary blow station,
for example of the type manufactured by Bekum Maschinenfabriken
Gmbh, of Berlin. This machine may be modified with a special
attachment for prepinching the parison as illustrated.
Turning to FIG. 3, extruder 40 is shown in the process of extruding
a hot, tubular plastic parison 42 which has been sealed at its
outer end 44 by pinching unit 48. Pinching unit 46 is shown to
comprise a pair of sealing bars 48 positioned upon reciprocating
arms 50 so that, in the manner programmed, they are opened as shown
to allow the parison 42 to pass, and then intermittently close
together to provide a transverse seal 44 at the outer end of the
parison.
FIG. 3 also shows cutting blade 52 positioned on horizontally
swinging arm 54, which swings through the parison 42 to cut it at
the appropriate time.
Mold halves 56, 58 each defining a mold chamber 60 of a shape
complementary to the shape of half of bag 10, is also shown in FIG.
3.
After parison 42 has lowered between mold halves 56, 58, the
tubular extruded parison is exposed in its interior to a low
pressure (about 8 p.s.i.g.) to cause it to balloon outwardly as
shown in FIG. 3 until its transverse dimension approximates the
width of mold chambers 60. The portion of the parison that defines
shoulders 12 may be extruded with a thicker wall.
Then, the mold halves 56, 58 are closed, as shown in FIG. 4, to
cause the parison to be transversely collapsed to assume the
general shape of chambers 60. However, parison 42 has been
ballooned so that it exceeds the transverse dimension of the mold
chamber 60, and thus overlaps it generally on all sides thereof, as
illustrated in the elevational view of FIG. 9.
The sealing edges 66 of mold chamber 60 may be approximately 0.015
to 0.05 inch wider, typically 0.03 inch, being surrounded on the
outside by recess 65 formed in face 68 of each mold half, to form a
thinned seal line 67, defining the newly-formed bag 10, which is
surrounded by a flash portion 70 of the parison. Thereafter, knife
52 cuts the parison 42, and the closed mold halves 56, 58 held
within mold retainer assembly 61 are horizontally moved, as shown
in FIG. 5, in the conventional manner of the Bekum machine, out
from under extruder 40 to a position under blow tube assembly
62.
As shown in FIGS. 6 and 7 blow tubes 64 move downwardly from
assembly 62, to pass through apertures 68 defined in the mold
halves, and through sleeve portions 16 defined in the newly-formed
bag in the closed mold, to penetrate into the bag interior.
Tubes 64 may be proportioned to sealingly pass through the bores of
sleeves 16 to assist in the formation thereof. Then relatively high
pneumatic pressure (for example 90 p.s.i.g.) is applied through
tubes 64 to the bag interior, to blow mold the bag to its final
configuration intimately corresponding to the shape of the mold
chambers 60. A perspective view of this step is shown in FIG. 7,
with an opened elevational view of the same step being shown in
FIG. 9.
Thereafter, mold halves 56 reopen as shown in FIG. 8, and
newly-formed bag 10 drops out of the apparatus. Thereafter, the
flash portions 70 of the parison which are outside of thin seal
line 67, formed by mold chamber edges 66, may be stripped off, and
the auxiliary members 22, 23, and donor tubing 18 may be added, to
provide a blood bag 10 as shown in FIGS. 1 and 2.
Each mold half 56, 58 defines a tail-forming section 72 including a
raised portion 74 to define the tail seal 26 and thin pierceable
portion 28 of the bag. Also, each mold half defines an access
tube-forming portion 76 comprising a complementary shaped area for
forming the sleeve 16 and web member 25, as well as perforatable
portion 27. Raised linear portions on the mold define thin,
frangible portions 29.
The above has been offered for illustrative purposes only, and is
not for the purpose of limiting the invention of this application,
which is as defined in the claims below.
* * * * *